Transmission of discovery signal in small cells while in off state

ABSTRACT

[Object] To provide a mechanism that enables a signal for measurement to be transmitted in a partial frequency band and measured on the terminal apparatus side. 
     [Solution] An apparatus that operates a small cell, the apparatus including: a processing unit configured to select, from among one or more unit frequency bands in an off state in a plurality of unit frequency bands that may be brought into an on state for uplink communication or downlink communication in the small cell, the unit frequency band in an off state to be used for transmission of a discovery signal to enable measurement in the unit frequency band in an off state.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/741,576, filed Jan. 3, 2018, which is based on PCT filingPCT/JP2016/067158, filed Jun. 9, 2016, which claims priority to JP2015-174902, filed Sep. 4, 2015, the entire contents of each areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and a method.

BACKGROUND ART

Wireless communication environment in recent years faces a problem of arapid increase in data traffic. Hence, in 3GPP, installing a largenumber of small cells in a macro cell to increase network density,thereby distributing traffic, has been under study. Such a technologyutilizing small cells is referred to as small cell enhancement. Notethat small cells may conceptually include various types of cells (e.g.,a femto cell, a nano cell, a pico cell, a micro cell, and the like) thatare smaller than a macro cell and are arranged to overlap a macro cell.However, an increase in small cells may cause an increase in inter-cellinterference and lead to large power consumption of the entire network;hence, in Patent Literature 1 below, a technology of adaptively settinga small cell in a sleep state has been developed.

In addition, as one way to expand radio resources, utilization of afrequency band of 6 GHz or more, which is called a milli-wave zone, hasbeen under study. However, since the milli-wave zone has strongstraightness and exhibits large radio propagation attenuation,utilization in a small cell smaller than a macro cell is expected. Undera situation in which the broad frequency band of the milli-wave zone isnot entirely used, part of the frequency band can be turned on/off inthe small cell. Further, in regard to a frequency band in an off state,a signal for measurement to enable measurement of quality on theterminal apparatus side is transmitted from a base station.

CITATION LIST Patent Literature

Patent Literature 1: JP 2015-61262A

DISCLOSURE OF INVENTION Technical Problem

However, transmitting a signal for measurement using the whole of thebroad frequency band of the milli-wave zone imposes a large burden onthe base station side in terms of electric power. In addition, measuringa signal for measurement in the whole of the broad frequency bandimposes a large burden also on the terminal apparatus side in terms ofelectric power. Therefore, it is desirable to provide a mechanism thatenables a signal for measurement to be transmitted in a partialfrequency band and measured on the terminal apparatus side.

Solution to Problem

According to the present disclosure, there is provided an apparatus thatoperates a small cell, the apparatus including: a processing unitconfigured to select, from among one or more unit frequency bands in anoff state in a plurality of unit frequency bands that may be broughtinto an on state for uplink communication or downlink communication inthe small cell, the unit frequency band in an off state to be used fortransmission of a discovery signal to enable measurement in the unitfrequency band in an off state.

In addition, according to the present disclosure, there is provided anapparatus that connects to a small cell, the apparatus including: aprocessing unit configured to perform measurement regarding a discoverysignal that has been transmitted using a unit frequency band selectedfrom one or more unit frequency bands in an off state in a plurality ofunit frequency bands that may be brought into an on state for uplinkcommunication or downlink communication in the small cell.

In addition, according to the present disclosure, there is provided amethod including: selecting, by a processor, from among one or more unitfrequency bands in an off state in a plurality of unit frequency bandsthat may be brought into an on state for uplink communication ordownlink communication in a small cell, the unit frequency band in anoff state to be used for transmission of a discovery signal to enablemeasurement in the unit frequency band in an off state.

In addition, according to the present disclosure, there is provided amethod including: performing, by a processor, measurement regarding adiscovery signal that has been transmitted using a unit frequency bandselected from one or more unit frequency bands in an off state in aplurality of unit frequency bands that may be brought into an on statefor uplink communication or downlink communication in a small cell.

Advantageous Effects of Invention

As described above, according to the present disclosure, a mechanismthat enables a signal for measurement to be transmitted in a partialfrequency band and measured on the terminal apparatus side is provided.Note that the effects described above are not necessarily limitative.With or in the place of the above effects, there may be achieved any oneof the effects described in this specification or other effects that maybe grasped from this specification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram for describing an overview of a systemaccording to an embodiment of the present disclosure.

FIG. 2 is an explanatory diagram for describing component carriers.

FIG. 3 is an explanatory diagram for describing on/off of componentcarriers.

FIG. 4 is an explanatory diagram for describing a DRS.

FIG. 5 is a sequence diagram illustrating an example of the flow of aprocess related to measurement of a DRS.

FIG. 6 is a block diagram illustrating an example of the configurationof a small cell base station according to the embodiment.

FIG. 7 is a block diagram illustrating an example of the configurationof a terminal apparatus according to the embodiment.

FIG. 8 is an explanatory diagram for describing a technical featureaccording to a first embodiment.

FIG. 9 is an explanatory diagram for describing a technical featureaccording to the embodiment.

FIG. 10 is an explanatory diagram for describing a technical featureaccording to the embodiment.

FIG. 11 is a sequence diagram illustrating an example of the flow of aprocess of a DRS request procedure executed in a system according to theembodiment.

FIG. 12 is an explanatory diagram for describing a technical featureaccording to a second embodiment.

FIG. 13 is a sequence diagram illustrating an example of the flow of aprocess of a CC state change request procedure executed in a system 1according to the embodiment.

FIG. 14 is a block diagram illustrating a first example of a schematicconfiguration of an eNB.

FIG. 15 is a block diagram illustrating a second example of theschematic configuration of the eNB.

FIG. 16 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 17 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. Notethat, in this specification and the appended drawings, structuralelements that have substantially the same function and structure aredenoted with the same reference numerals, and repeated explanation ofthese structural elements is omitted.

Note that description will be given in the following order.

1. Introduction

1.1. Small cell

1.2. Carrier aggregation

1.3. On/off of component carrier

2. Configuration examples

2.1. Configuration example of small cell base station

2.2. Configuration of terminal apparatus

3. First embodiment

3.1. Technical problems

3.2. Technical features

3.3. Flow of process

4. Second embodiment

4.1. Technical problem

4.2. Technical features

4.3. Flow of process

5. Application examples

6. Conclusion 1. Introduction 1.1. Small Cell

FIG. 1 is an explanatory diagram for describing an overview of a system1 according to an embodiment of the present disclosure. As illustratedin FIG. 1, the system 1 includes a wireless communication apparatus 10,a terminal apparatus 20, and a communication control apparatus 30.

In the example of FIG. 1, the communication control apparatus 30 is amacro cell base station. The macro cell base station 30 provides awireless communication service for one or more terminal apparatuses 20located inside a macro cell 31. The macro cell base station 30 isconnected to a core network 15. The core network 15 is connected to apacket data network (PDN) 16 via a gateway apparatus (not illustrated).The macro cell 31 may be operated in accordance with any wirelesscommunication scheme, such as long term evolution (LTE), LTE-advanced(LTE-A), GSM (registered trademark), UMTS, W-CDMA, CDMA200, WiMAX,WiMAX2, or IEEE802.16, for example. Note that without being limited tothe example of FIG. 1, a control node in the core network 15 or the PDN16 (a host node of the macro cell base station) may have a function ofcontrolling wireless communication in a macro cell and a small cell in acooperative manner. Note that the macro cell base station may also bereferred to as a Macro eNodeB.

The wireless communication apparatus 10 is a small cell base stationthat operates a small cell 11. Typically, the small cell base station 10is authorized to allocate radio resources to the terminal apparatus 20that connects to the own apparatus. However, allocation of radioresources may be at least partially entrusted to the communicationcontrol apparatus 30 for cooperative control. A wireless communicationapparatus 20 may be a small cell base station fixedly installed asillustrated in FIG. 1, or may be a dynamic access point (AP) thatdynamically operates the small cell 11. Note that the small cell basestation may also be referred to as a pico eNB or a Femto eNB.

The terminal apparatus 20 connects to the macro cell base station 30 orthe small cell base station 10 to enjoy a wireless communicationservice. For example, the terminal apparatus 20 that connects to thesmall cell base station 10 receives a control signal from the macro cellbase station 30, and receives a data signal from the small cell basestation 10. The terminal apparatus 20 is also called a user. The usermay also be called user equipment (UE). Here, UE may be UE defined inLTE or LTE-A, or more generally may mean communication equipment.

1.2. Carrier Aggregation

A technology related to carrier aggregation prescribed in LTE Release 10is described below.

(1) Component Carrier

Carrier aggregation is a technology of improving throughput ofcommunication by forming a communication channel between a base stationand a terminal apparatus by aggregating a plurality of unit frequencybands supported in LTE, for example. Individual unit frequency bandsincluded in one communication channel formed by carrier aggregation arereferred to as component carriers (CCs). Here, a CC may be a CC definedin LTE or LTE-A, or more generally may mean a unit frequency band.

In LTE Release 10, it is possible to aggregate five CCs at maximum. Inaddition, one CC has a width of 20 MHz. Note that the CCs to beaggregated may be arranged consecutively on a frequency axis, or may bearranged apart from each other. Moreover, which CC to aggregate and usecan be set for each terminal apparatus.

The plurality of CCs that are aggregated are classified into one primarycomponent carrier (PCC) and a secondary component carrier (SCC) otherthan the PCC. The PCC is different for each terminal apparatus. Sincethe PCC is the most important CC, it is desirable that the CC with themost stable communication quality be selected.

FIG. 2 is an explanatory diagram for describing component carriers. Inthe example illustrated in FIG. 2, a situation in which two pieces of UEuse some of five CCs in aggregation is illustrated. In detail, UE1 usesCC1, CC2, and CC3 in aggregation, and UE2 uses CC2 and CC4 inaggregation. Moreover, the PCC of UE1 is CC2. The PCC of UE2 is CC4.

Here, selection of a PCC is dependent on implementation. An SCC ischanged by deleting the SCC and adding another SCC. That is, it isdifficult to directly change an SCC.

(2) Formation and Change of PCC

In the case where a terminal apparatus transitions from an RRC Idlestate to an RRC Connected state, the CC in which connection isestablished first is the PCC. A change of the PCC is performed through aprocedure similar to handover.

A PCC is formed through a procedure called Connection establishment.This procedure is a procedure started with a request from the terminalapparatus side used as a trigger.

A PCC is changed through a procedure called Connection Reconfiguration.This procedure includes transmission and reception of handover messages.This procedure is a procedure started from the base station side.

(3) Addition of SCC

An SCC is added through a procedure called Connection Reconfiguration.This procedure is a procedure started from the base station side. An SCCis added to a PCC and belongs to the PCC. Adding an SCC is also referredto as activating an SCC.

(4) Deletion of SCC

An SCC is deleted through a procedure called Connection Reconfiguration.This procedure is a procedure started from the base station side. Inthis procedure, a specific SCC designated in a message is deleted. Notethat deletion of an SCC is performed also through a procedure calledConnection Re-establishment. This procedure is a procedure started fromthe terminal apparatus side. Through this procedure, all the SCCs aredeleted. Deleting an SCC is also referred to as deactivating an SCC.

(5) Special Role of PCC

A PCC has a special role different from that of an SCC. For example,transmission and reception of NAS signaling in Connection establishmentis performed only in the PCC. In addition, transmission of a physicaluplink control channel (PUCCH) is performed only in the PCC. Note thatexamples of an uplink control signal include ACK or NACK indicatingsuccess for failure of reception for data transmitted in downlink, ascheduling request, and the like. Moreover, a procedure from detectionof Radio Link Failure to Connection Re-establishment is also performedonly in the PCC.

1.3. On/off of Component Carrier

In regard to carrier aggregation, a technology prescribed in LTE Release12 is described below.

In LTE Release 12, a scenario is shown in which a macro cell basestation and a small cell base station use different frequencies. Forexample, a frequency of approximately 2 GHz may be allocated to themacro cell base station, and a high frequency such as 5 GHz may beallocated to the small cell base station.

Moreover, LTE Release 12 prescribes that at least part of a frequencyband is intermittently turned on/off (i.e., brought into an on state/anoff state) by a base station. The first purpose of this is to reducepower consumption by small cell base stations, which are large innumber. In addition, the second purpose is to reduce interference byturning off a frequency band that does not need to be used.

FIG. 3 is an explanatory diagram for describing on/off of componentcarriers. FIG. 3 illustrates examples of CCs provided by a base station;CC1 and CC2 are in an on state, and CC3 is in an off state. A terminalapparatus can activate a CC in an on state, thereby performing uplinkcommunication or downlink communication using the CC with the basestation. That is, CCs in an on state are candidates for CCs that can beactivated. In regard to CC3 in an off state, the base station transmitsa signal for measurement to enable measurement of quality on theterminal apparatus side. This signal for measurement may also be calleda discovery reference signal (DRS). Here, a DRS may be a DRS defined inLTE or LTE-A, or more generally may mean a signal for measurement (e.g.,a discovery signal). The terminal apparatus measures quality of adownlink channel of CC3 in an off state with the DRS, and reports ameasurement result to a cell base station. The base station determineswhether or not to turn on CC3 in an off state on the basis of thismeasurement result.

FIG. 4 is an explanatory diagram for describing a DRS. FIG. 4schematically illustrates transmission timing of the DRS. As illustratedin FIG. 4, the DRS may be transmitted intermittently and periodically. Acycle may be 50 milliseconds (ms), for example. In addition, this cycleis variable, and cycle setting information is reported from the basestation to the terminal apparatus. In contrast, a cell specificreference signal (CRS), which is a reference signal, is inserted intoall sub-frames, and its cycle is 1 ms, for example.

FIG. 5 is a sequence diagram illustrating an example of the flow of aprocess related to measurement of a DRS. As illustrated in FIG. 5,first, the base station transmits a DRS (step S12). On that occasion,the base station is assumed to transmit the DRS periodically with atransmission cycle and a CC set in common with the terminal apparatuspreliminarily, in the CC in an off state. The terminal apparatusperforms measurement of the DRS in accordance with preliminary setting(step S14), and transmits the measurement result to the base station(step S16). In this specification, measurement of the DRS is alsoreferred to as measurement, and the measurement result is also referredto as a measurement report. Note that the measurement report istransmitted using uplink of a CC in an on state. The base stationdetermines on/off of a CC on the basis of the measurement report (stepS18). For example, the base station turns on a CC in an off state thatis to be turned on, and turns off a CC in an on state that is to beturned off.

In typical implementation, not a macro cell base station but a smallcell base station turns on/off component carriers. Therefore, thefollowing description is given in regard to a small cell base stationthat turns on/off component carriers. As a matter of course, this doesnot narrow the scope of application of the present technology, and thepresent technology is also applicable to a macro cell base station andthe like.

2. Configuration Examples 2.1. Configuration Example of Small Cell BaseStation

Next, the configuration of the small cell base station 10 according toan embodiment of the present disclosure will be described with referenceto FIG. 6. FIG. 6 is a block diagram illustrating an example of theconfiguration of the small cell base station 10 according to anembodiment of the present disclosure. Referring to FIG. 6, the smallcell base station 10 includes an antenna unit 110, a wirelesscommunication unit 120, a network communication unit 130, a storage unit140, and a processing unit 150.

(1) Antenna Unit 110

The antenna unit 110 radiates a signal output by the wirelesscommunication unit 120, in the form of radio waves, into space. Theantenna unit 110 also converts radio waves in space into a signal, andoutputs the signal to the wireless communication unit 120.

(2) Wireless Communication Unit 120

The wireless communication unit 120 transmits and receives signals. Forexample, the wireless communication unit 120 transmits a downlink signalto the terminal apparatus and receives an uplink signal from theterminal apparatus.

(3) Network Communication Unit 130

The network communication unit 130 transmits and receives information.For example, the network communication unit 130 transmits information toother nodes and receives information from other nodes. For example, theother nodes include other base stations and a core network node.

(4) Storage Unit 140

The storage unit 140 temporarily or permanently stores a program andvarious data for operation of the small cell base station 10.

(5) Processing Unit 150

The processing unit 150 provides various functions of the small cellbase station 10. The processing unit 150 includes a transmissionprocessing unit 151 and a reporting unit 153. Note that the processingunit 150 may further include a structural element other than thesestructural elements. That is, the processing unit 150 may performoperation other than the operation of these structural elements.

The operation of the transmission processing unit 151 and the reportingunit 153 will be described in detail later.

2.2. Configuration of Terminal Apparatus

Next, an example of the configuration of the terminal apparatus 20according to an embodiment of the present disclosure will be describedwith reference to FIG. 7. FIG. 7 is a block diagram illustrating anexample of the configuration of the terminal apparatus 20 according toan embodiment of the present disclosure. Referring to FIG. 7, theterminal apparatus 20 includes an antenna unit 210, a wirelesscommunication unit 220, a storage unit 230 and a processing unit 240.

(1) Antenna Unit 210

The antenna unit 210 radiates a signal output by the wirelesscommunication unit 220, in the form of radio waves, into space. Theantenna unit 210 also converts radio waves in space into a signal, andoutputs the signal to the wireless communication unit 220.

(2) Wireless Communication Unit 220

The wireless communication unit 220 transmits and receives signals. Forexample, the wireless communication unit 220 receives a downlink signalfrom the base station and transmits an uplink signal to the basestation.

(3) Storage Unit 230

The storage unit 230 temporarily or permanently stores a program andvarious data for operation of the terminal apparatus 20.

(4) Processing Unit 240

The processing unit 240 provides various functions of the terminalapparatus 20. The processing unit 240 includes a measurement processingunit 241 and a requesting unit 243. Note that the processing unit 240may further include a structural element other than these structuralelements. That is, the processing unit 240 may perform operation otherthan the operation of these structural elements.

The operation of the measurement processing unit 241 and the requestingunit 243 will be described in detail later.

3. First Embodiment 3.1. Technical Problems (1) First Problem

A milli-wave zone has a broad frequency band. Transmitting a DRS usingall the CCs included in the broad frequency band of the milli-wave zoneimposes a large burden on the small cell base station 10 in terms ofelectric power. Furthermore, transmitting and receiving a DRS using allthe CCs included in the broad frequency band of the milli-wave zone mayalso cause an increase in inter-cell interference as well as an increasein power consumption.

Hence, the present embodiment provides a mechanism in which the smallcell base station 10 can transmit a DRS in some of a plurality of CCs inan off state.

Here, it is assumed that in the milli-wave zone, a bandwidth of a CC,which is set at 20 MHz in LTE Release 10, can be changed to widerbandwidths such as 40 MHZ, 80 MHz, or 160 MHz, for example. In the casewhere such enlargement of bandwidth is carried out, a mechanism in whicha DRS can be transmitted in some of CCs and measured can be said to beeffective for a reduction in burden in terms of electric power.

(2) Second Problem

It is assumed that there are a plurality of types of bandwidths of CCs.As examples, a CC with a bandwidth of 20 MHz, a CC with a bandwidth of40 MHz, and a CC with a bandwidth of 80 MHz are assumed. In addition, itis assumed to be possible to select, for each terminal apparatus,whether to use a bandwidth of 80 MHz as one CC with a bandwidth of 80MHz, as two CCs with a bandwidth of 40 MHz, or as four CCs with abandwidth of 20 MHz. For example, in the case where a terminal apparatushas only ability to handle a bandwidth of 20 MHz, it is desirable that aCC with a bandwidth of 20 MHz be brought into an on state. Therefore,the terminal apparatus only needs to perform measurement regarding a CCwith a bandwidth of 20 MHz, and measurement regarding a CC with abandwidth of 80 MHz, for example, is unnecessary. Since a CC with abandwidth for which such measurement is to be performed may differ foreach terminal apparatus, it is inefficient to transmit a DRS in CCs withthe same bandwidth in common for all terminal apparatuses.

Hence, the present embodiment provides a mechanism in which a terminalapparatus can request a CC in which a base station transmits a DRS.

(3) Third Problem

Measuring a DRS in all the CCs included in the broad frequency bandimposes a large burden in terms of electric power on not only the basestation but also the terminal apparatus side. Particularly in the casewhere a base station transmits a DRS in some of CCs as described in thefirst embodiment, measuring the DRS in all the CCs on the terminalapparatus side causes waste in terms of power consumption.

In regard to this point, under present circumstances, with which cycle aDRS is transmitted for each CC is reported to the terminal apparatusside preliminarily by RRC signaling. However, under a situation in whichwhether or not a DRS is transmitted may be switched frequently for eachCC, reporting to the terminal apparatus cannot be said to be sufficient.

Hence, the present embodiment provides a mechanism in which informationregarding a DRS can be dynamically reported to a terminal apparatus.

3.2. Technical Features (1) Provision of DRS

The small cell base station 10 (e.g., the transmission processing unit151) selects a CC in an off state to be used for transmission of a DRSto enable measurement in one or more CCs in an off state, from among aplurality of CCs that may be brought into an on state for uplinktransmission or downlink transmission in a small cell. Thus, the smallcell base station 10 can transmit the DRS selectively in a partial bandof the broad milli-wave zone, which enables a reduction in powerconsumption and also a reduction in inter-cell interference. The smallcell base station 10 transmits the DRS using the selected CC.

For example, the small cell base station 10 (e.g., the transmissionprocessing unit 151) may increase CCs used for transmission of the DRSin a stepwise manner. Conversely, the small cell base station 10 mayreduce CCs used for transmission of the DRS in a stepwise manner. Thismakes it possible to provide the DRS in just enough number of CCs, inaccordance with an increase tendency or a decrease tendency of thenumber of users in a cell, for example. As another example, the smallcell base station 10 may use all the CCs that can be brought into an onstate for transmission of the DRS in a stroke.

Here, selection of a CC for providing the DRS is specifically describedwith reference to FIG. 8 illustrating an example of a configuration ofCCs. The CCs illustrated in FIG. 8 are CCs that can be brought into anon state, and are CCs that may be used for transmission of the DRS. CC1to CC4 are CCs with a bandwidth of 20 MHz. CC5 and CC6 are CCs with abandwidth of 40 MHz. CC7 is a CC with a bandwidth of 80 MHz. Forexample, in the case where all the CCs are in an off state, the smallcell base station 10 provides the DRS in CC1. Then, in the case whereCC1 is turned on, the small cell base station 10 provides the DRS inCC2. Then, in the case where CC2 is turned on, the small cell basestation 10 provides the DRS in CC3. Then, in the case where CC3 isturned on, the small cell base station 10 provides the DRS in CC4. As amatter of course, the small cell base station 10 may provide the DRS inCC5 to CC7, or may provide the DRS in a plurality of CCs. In addition,in the case where there is a change in a CC for providing the DRS, thesmall cell base station 10 reports the change to the terminal apparatus20. This point will be described in detail later.

In addition, the small cell base station 10 (e.g., the transmissionprocessing unit 151) may select a CC to be used for transmission of theDRS, on the basis of a measurement result of the DRS in the terminalapparatus 20 that connects to the small cell. This makes it possible toprovide the DRS in a CC corresponding to fluctuation of radio-waveenvironment, for example.

The terminal apparatus 20 (e.g., the measurement processing unit 241)performs measurement regarding the DRS that has been transmitted using aCC selected from one or more CCs in an off state, among a plurality ofCCs that may be brought into an on state for uplink transmission ordownlink transmission in the small cell. Thus, the terminal apparatus 20can perform measurement in a partial band of the broad milli-wave zone,which enables a reduction in power consumption. In addition, theterminal apparatus 20 reports a measurement report to the small cellbase station 10. The small cell base station 10 can select a CC in anoff state to be used for transmission of the DRS on the basis of thismeasurement report.

Here, a CC in the present embodiment is assumed to be a CC in themilli-wave zone, which is a frequency band of 6 GHz or more.

(2) Reporting of Setting Information Regarding DRS (2.1) First SettingInformation

The small cell base station 10 (e.g., the reporting unit 153) reportsinformation indicating a CC that can be brought into an on state, to theterminal apparatus 20 that connects to the small cell. Thus, theterminal apparatus 20 can find at least a CC in which the DRS may betransmitted, which makes it possible to avoid measurement in a frequencyband with no possibility of transmission of the DRS. Informationindicating a CC that can be brought into an on state is also referred toas CC configuration information below.

A CC that can be brought into an on state may be associated with a CCused for transmission of the DRS. For example, this association may be acombination of a CC used for transmission of the DRS and a CC that maybe brought into an on state on the basis of a measurement report of theDRS provided in the CC. Moreover, this association may be abidirectional relationship. For example, in the case where CCconfiguration information includes information indicating CC1 to CC7illustrated in FIG. 8, CC2 may be brought into an on state on the basisof a measurement report of CC1, or CC1 may be brought into an on stateon the basis of a measurement report of CC2. As a matter of course, atleast one of CC2 to CC7 may be brought into an on state on the basis ofthe measurement report of CC1. As will be described later, the terminalapparatus 20 may request a CC in which provision of the DRS is to bestarted. In the case where CC configuration information including theabove association is reported from the small cell base station 10, theterminal apparatus 20 can request a start of provision of the DRS in adesired CC among CCs that may be brought into an on state depending onthe contents of a measurement report.

A CC that can be brought into an on state may include a band differentfrom that of an associated CC used for transmission of the DRS. That is,a CC subjected to measurement does not need to coincide with a CCbrought into an on state. For example, in the example illustrated inFIG. 8, CC6 may be brought into an on state on the basis of ameasurement result of CC1.

For reporting of CC configuration information, for example, means suchas system information (SI), RRC signaling or a physical downlink controlchannel (PDCCH) may be used. Moreover, reporting of CC configurationinformation may be performed periodically, or may be performed at anytiming (e.g., whenever there is a change). Note that CC configurationinformation may be static or quasi-static information.

(2.2) Second Setting Information

The small cell base station 10 (e.g., the reporting unit 153) reportsinformation regarding arrangement of the DRS in each CC, to the terminalapparatus 20 that connects to the small cell. Here, arrangement of theDRS refers to a transmission cycle, a frequency in each CC, and thelike. Reporting of this information enables the terminal apparatus 20 toperform measurement appropriately. This information is also referred toas DRS arrangement information below.

For reporting of DRS arrangement information, for example, means such asSI, RRC signaling or a PDCCH may be used. Moreover, reporting of DRSarrangement information may be performed periodically, or may beperformed at any timing (e.g., whenever there is a change). Note thatDRS arrangement information may be static or quasi-static information.

(2.3) Third Setting Information

The small cell base station 10 (e.g., the reporting unit 153) reportsinformation indicating a CC to be used for transmission of the DRS, tothe terminal apparatus 20 that connects to the small cell. Reporting ofthis information enables the terminal apparatus 20 to performmeasurement on a CC actually used for transmission of the DRS, among CCsincluded in the broad frequency band. This information is also referredto as DRS state information below.

Here, FIGS. 9 and 10 illustrate examples of DRS state information. InFIG. 9, a value of a bit position corresponding to each of CC1 to CC7illustrated in FIG. 8 indicates whether each CC is used for transmissionof the DRS. The first bit corresponds to CC1, the second bit correspondsto CC2, the third bit corresponds to CC3, the fourth bit corresponds toCC4, the fifth bit corresponds to CCS, the sixth bit corresponds to CC6,and the seventh bit corresponds to CC7. The bit value 0 indicates thatthe CC is not used for transmission of the DRS, and the bit value 1indicates that the CC is used for transmission of the DRS. In FIG. 10, avalue of a bit position corresponding to each of CC1 to CC4 illustratedin FIG. 8 indicates whether each CC is used for transmission of the DRS.Information expression in such a form is effective in the case where theDRS is transmitted in a CC with a width of 20 MHz. In this case, four20-MHz DRSs may be used in a bundle in place of a DRS for 80 MHz.

In addition, the small cell base station 10 may report informationindicating a CC of which use in transmission of the DRS is to be startedor stopped. That is, in the case where there is a change in a CC to beused for transmission of the DRS, the small cell base station 10 mayreport information indicating the difference.

Moreover, the small cell base station 10 may report DRS stateinformation in the case where there is a change in a CC to be used fortransmission of the DRS. That is, the small cell base station 10 mayreport DRS state information at timing of a change in a CC to be usedfor transmission of the DRS. This enables the terminal apparatus 20 toperform measurement on an appropriate CC, even in the case where thereis a change in a CC to be used for transmission of the DRS, and enablesa reduction in power consumption. As a matter of course, reporting ofDRS arrangement information may be performed periodically. The cycle maybe approximately 40 ms, for example.

For reporting of DRS state information, for example, means such as SI,RRC signaling or a PDCCH may be used. However, it is desirable to usemeans capable of instantaneous reporting, such as a PDCCH or SI, forexample, for reporting of DRS state information. This enables theterminal apparatus 20 to switch a measurement-target CC instantaneouslyeven under a situation in which a CC in which the DRS is transmitted isswitched frequently.

(3) Request for Change of CC to be used for Transmission of DRS

The terminal apparatus 20 (e.g., the requesting unit 243) may request achange of a CC to be used for transmission of the DRS. For example, theterminal apparatus 20 may report information indicating a CC in an offstate to be requested to be used for transmission of the DRS, to thesmall cell base station 10. That is, the terminal apparatus 20 mayrequest a start of provision of the DRS. Then, the small cell basestation 10 (e.g., a DRS transmission processing unit 151) may select aCC to be used for transmission of the DRS on the basis of the requestfrom the terminal apparatus 20 that connects to the small cell. Thisenables provision of the DRS to be started quickly in a CC in which theterminal apparatus 20 desires to perform measurement. Similarly, theterminal apparatus 20 can also request a stop of provision of the DRS,in which case unnecessary provision of the DRS can be stopped quickly.Such a request is also referred to as a DRS request below.

The terminal apparatus 20 may designate a CC related to a DRS request onthe basis of CC configuration information. For example, the terminalapparatus 20 designates a CC in which provision of the DRS is to berequested to be started or stopped, from among a CC in which measurementhas been performed and one or more CCs associated in the CCconfiguration information. For example, in the case where CCconfiguration information includes information indicating CC1 to CC7illustrated in FIG. 8, the terminal apparatus 20 may requesttransmission of the DRS in at least one of CC2 to CC7 in the case wheremeasurement has been performed in CC1.

This DRS request may be reported together with a measurement report, forexample. In that case, the small cell base station 10 can select whetheror not to start provision of the DRS on the basis of both themeasurement report and the DRS request. Note that being reportedtogether may mean concurrent reporting, may mean serial reporting, ormay mean being reported included in the same signal or differentsignals.

(4) On/off of CC

The small cell base station 10 (e.g., the transmission processing unit151) selects a CC to be brought into an on state or brought into an offstate. For example, the small cell base station 10 may make a selectionon the basis of a measurement result from the terminal apparatus 20 thatconnects to the small cell. This makes it possible to appropriately turnon/off a CC in accordance with fluctuation of radio-wave environment,for example.

3.3. Flow of Process

FIG. 11 is a sequence diagram illustrating an example of the flow of aprocess of a DRS request procedure executed in the system 1 according tothe present embodiment. As illustrated in FIG. 11, this sequenceinvolves the small cell base station 10 and the terminal apparatus 20.

First, the small cell base station 10 transmits setting information tothe terminal apparatus 20 (step S102). This setting information includesCC configuration information, DRS arrangement information, and DRS stateinformation. CC configuration information includes informationindicating a CC used for transmission of the DRS and information beingassociated with the CC and indicating a CC that can be brought into anon state.

Then, the small cell base station 10 transmits the DRS in accordancewith the setting information (step S104). Specifically, the small cellbase station 10 transmits the DRS in a CC to be used for transmission ofthe DRS that is indicated by the DRS state information, among CCsindicated by the CC configuration information, with an arrangementindicated by the DRS arrangement information.

Next, the terminal apparatus 20 performs measurement of the DRS on thebasis of the received setting information (step S106), and transmits aDRS request together with a measurement report to the small cell basestation 10 (step S108). Note that the measurement report and the DRSrequest may be transmitted as different messages. Next, the small cellbase station 10 selects a CC to be used for transmission of the DRS onthe basis of the received measurement report and DRS request (stepS110), and transmits DRS state information to the terminal apparatus 20in accordance with a selection result (step S112). Then, the small cellbase station 10 transmits the DRS in a CC of which use has been reportedby the DRS state information (i.e., the CC selected in step 5110) (stepS114).

Then, the terminal apparatus 20 performs measurement on the basis of thereceived DRS state information (step S116), and transmits a measurementreport to the small cell base station 10 (step S118). Then, the smallcell base station 10 determines on/off of a CC on the basis of themeasurement report (step S120).

After the above steps, the process ends.

4. Second Embodiment 4.1. Technical Problem

In the first embodiment, a CC is brought into an on state on the basisof determination on the base station side. Therefore, there is a casewhere CCs are brought into an on state in a stepwise manner up to awidth of 80 MHz; for a terminal apparatus requiring immediate use of aCC with a width of 80 MHz, for example, a long time lag occurs until therequirement is satisfied. Such a time lag may cause a decrease inthroughput, or deterioration of Quality of Service (QoS) of a servicerequiring low delay.

Hence, the present embodiment provides a mechanism in which a terminalapparatus can request a CC to be brought into an on state by a basestation.

4.2. Technical Features (1) Request for State Change of CC

The terminal apparatus 20 (e.g., the requesting unit 243) may request astate change of a CC. For example, the terminal apparatus 20 may reportinformation indicating a CC to be requested to be brought into an onstate to the small cell base station 10. That is, the terminal apparatus20 may request turning on of a CC. Then, the small cell base station 10(e.g., the DRS transmission processing unit 151) may select a CC to bebrought into an on state on the basis of the request from the terminalapparatus 20 that connects to the small cell. This makes it possible toshorten a time lag until a CC that the terminal apparatus 20 desires tobe brought into an on state (typically, a CC desired to be activatedafter being turned on) is actually brought into an on state. Similarly,the terminal apparatus 20 can also request bringing a CC into an offstate, in which case a time lag until a desired CC is actually broughtinto an off state can be shortened. Such a request is also referred toas a CC state change request below.

The terminal apparatus 20 may designate a CC related to a CC statechange request on the basis of CC configuration information. Forexample, the terminal apparatus 20 designates a CC to be requested to bebrought into an on state, from among a CC in which measurement has beenperformed and one or more CCs associated in the CC configurationinformation. For example, in the case where CC configuration informationincludes information indicating CC1 to CC7 illustrated in FIG. 8, theterminal apparatus 20 may request bringing at least one of CC1 to CC7into an on state in the case where measurement has been performed inCC1.

This CC state change request may be reported together with a measurementreport, for example. In that case, the small cell base station 10 candetermine on/off of a CC on the basis of both the measurement report andthe CC state change request. Note that being reported together may meanconcurrent reporting, may mean serial reporting, or may mean beingreported included in the same signal or different signals.

(2) Control of Transmission Cycle of DRS

The small cell base station 10 (e.g., the transmission processing unit151) controls a transmission cycle of the DRS. For example, the smallcell base station 10 may make a transmission cycle of the DRS differ foreach CC. In regard to a time lag between occurrence of a state changerequest and satisfaction of the request, in the case where an allowablelength of the time lag differs depending on the CC, it is effective tomake the transmission cycle differ. In particular, the small cell basestation 10 may make a transmission cycle of the DRS shorter for CCs withsmaller bandwidths. This can make a time lag shorter for CCs withsmaller bandwidths. This is because CCs with smaller bandwidths arerequired to be used in a higher degree in terms of a reduction in powerconsumption both in the small cell base station 10 and in the terminalapparatus 20, and are presumed to desire a shorter time lag.

FIG. 12 illustrates such an example in which a transmission cycle of theDRS is made shorter for CCs with smaller bandwidths. In the exampleillustrated in FIG. 12, a DRS for a bandwidth of 20 MHz, a DRS for abandwidth of 40 MHz, and a DRS for a bandwidth of 80 MHz are eachtransmitted in one CC with the corresponding bandwidth. In addition, theshortest transmission cycle is set in CC1, the longest transmissioncycle is set in CC7, and a transmission cycle with a length betweenthose in CC1 and CC7 is set in CCS.

4.3. Flow of Process

FIG. 13 is a sequence diagram illustrating an example of the flow of aprocess of a CC state change request procedure executed in the system 1according to the present embodiment. As illustrated in FIG. 13, thissequence involves the small cell base station 10 and the terminalapparatus 20.

First, the small cell base station 10 transmits setting information tothe terminal apparatus 20 (step S202), and transmits the DRS inaccordance with the setting information (step S204).

Then, the terminal apparatus 20 performs measurement of the DRS on thebasis of the received setting information (step S206), and transmits aCC state change request together with a measurement report to the smallcell base station 10 (step S208). Note that the measurement report andthe CC state change request may be transmitted as different messages.Next, the small cell base station 10 determines on/off of a CC on thebasis of the received measurement report and CC state change request(step S210).

After the above steps, the process ends.

5. Application Examples

The technology according to the present disclosure is applicable tovarious products. The small cell base station 10 may also beimplemented, for example, as any type of evolved Node B (eNB) such asmacro eNBs and small eNBs. Small eNBs may be eNBs that cover smallercells than the macrocells, such as pico eNBs, micro eNBs, or home(femto) eNBs. Instead, the small cell base station 10 may be implementedas another type of base station such as Nodes B or base transceiverstations (BTSs). The small cell base station 10 may include the mainapparatus (which is also referred to as base station apparatus) thatcontrols wireless communication and one or more remote radio heads(RRHs) that are disposed at different locations from that of the mainapparatus. Also, various types of terminals described below may functionas the small cell base station 10 by temporarily or semi-permanentlyexecuting the functionality of the base station. Furthermore, at leastsome of structural elements of the small cell base station 10 may berealized in a base station apparatus or a module for a base stationapparatus.

Further, the terminal apparatus 20 may be implemented, for example, as amobile terminal such as smartphones, tablet personal computers (PCs),notebook PCs, portable game terminals, portable/dongle mobile routers,and digital cameras, or an in-vehicle terminal such as car navigationapparatuses. Further, the terminal apparatus 20 may be implemented as amachine type communication (MTC) terminal for establishing a machine tomachine (M2M) communication. Furthermore, at least some of structuralelements of the terminal apparatus 20 may be implemented as a module(e.g., integrated circuit module including a single die) that is mountedon these terminals.

4.1. Application Examples for Base Station First Application Example

FIG. 14 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station apparatus 820. Each antenna 810 and the base stationapparatus 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or a plurality of antennaelements (e.g., a plurality of antenna elements constituting a MIMOantenna) and is used for the base station apparatus 820 to transmit andreceive a wireless signal. The eNB 800 may include the plurality of theantennas 810 as illustrated in FIG. 14, and the plurality of antennas810 may, for example, correspond to a plurality of frequency bands usedby the eNB 800. It should be noted that while FIG. 14 illustrates anexample in which the eNB 800 includes the plurality of antennas 810, theeNB 800 may include the single antenna 810.

The base station apparatus 820 includes a controller 821, a memory 822,a network interface 823, and a wireless communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of an upper layer of the base station apparatus 820.For example, the controller 821 generates a data packet from data in asignal processed by the wireless communication interface 825, andtransfers the generated packet via the network interface 823. Thecontroller 821 may generate a bundled packet by bundling data from aplurality of base band processors to transfer the generated bundledpacket. Further, the controller 821 may also have a logical function ofperforming control such as radio resource control, radio bearer control,mobility management, admission control, and scheduling. Further, thecontrol may be performed in cooperation with a surrounding eNB or a corenetwork node. The memory 822 includes a RAM and a ROM, and stores aprogram executed by the controller 821 and a variety of control data(such as, for example, terminal list, transmission power data, andscheduling data).

The network interface 823 is a communication interface for connectingthe base station apparatus 820 to the core network 824. The controller821 may communicate with a core network node or another eNB via thenetwork interface 823. In this case, the eNB 800 may be connected to acore network node or another eNB through a logical interface (e.g., S1interface or X2 interface). The network interface 823 may be a wiredcommunication interface or a wireless communication interface forwireless backhaul. In the case where the network interface 823 is awireless communication interface, the network interface 823 may use ahigher frequency band for wireless communication than a frequency bandused by the wireless communication interface 825.

The wireless communication interface 825 supports a cellularcommunication system such as long term evolution (LTE) or LTE-Advanced,and provides wireless connection to a terminal located within the cellof the eNB 800 via the antenna 810. The wireless communication interface825 may typically include a base band (BB) processor 826, an RF circuit827, and the like. The BB processor 826 may, for example, performencoding/decoding, modulation/demodulation, multiplexing/demultiplexing,and the like, and performs a variety of signal processing on each layer(e.g., L1, medium access control (MAC), radio link control (RLC), andpacket data convergence protocol (PDCP)). The BB processor 826 may havepart or all of the logical functions as described above instead of thecontroller 821. The BB processor 826 may be a module including a memoryhaving a communication control program stored therein, a processor toexecute the program, and a related circuit, and the function of the BBprocessor 826 may be changeable by updating the program. Further, themodule may be a card or blade to be inserted into a slot of the basestation apparatus 820, or a chip mounted on the card or the blade.Meanwhile, the RF circuit 827 may include a mixer, a filter, anamplifier, and the like, and transmits and receives a wireless signalvia the antenna 810.

The wireless communication interface 825 may include a plurality of theBB processors 826 as illustrated in FIG. 14, and the plurality of BBprocessors 826 may, for example, correspond to a plurality of frequencybands used by the eNB 800. Further, the wireless communication interface825 may also include a plurality of the RF circuits 827, as illustratedin FIG. 14, and the plurality of RF circuits 827 may, for example,correspond to a plurality of antenna elements. Note that FIG. 14illustrates an example in which the wireless communication interface 825includes the plurality of BB processors 826 and the plurality of RFcircuits 827, but the wireless communication interface 825 may includethe single BB processor 826 or the single RF circuit 827.

In the eNB 800 illustrated in FIG. 14, one or more structural elementsincluded in the small cell base station 10 (the transmission processingunit 151 and/or the reporting unit 153) described with reference to FIG.6 may be implemented by the wireless communication interface 825.Alternatively, at least some of these structural elements may beimplemented by the controller 821. As an example, a module whichincludes a part (for example, the BB processor 826) or all of thewireless communication interface 825 and/or the controller 821 may bemounted in the eNB 800, and the one or more structural elements may beimplemented by the module. In this case, the module may store a programfor causing the processor to function as the one or more structuralelements (i.e., a program for causing the processor to executeoperations of the one or more structural elements) and may execute theprogram. As another example, the program for causing the processor tofunction as the one or more structural elements may be installed in theeNB 800, and the wireless communication interface 825 (for example, theBB processor 826) and/or the controller 821 may execute the program. Asdescribed above, the eNB 800, the base station apparatus 820, or themodule may be provided as an apparatus which includes the one or morestructural elements, and the program for causing the processor tofunction as the one or more structural elements may be provided. Inaddition, a readable recording medium in which the program is recordedmay be provided.

In addition, in the eNB 800 illustrated in FIG. 14, the wirelesscommunication unit 120 described with reference to FIG. 6 may beimplemented by the wireless communication interface 825 (for example,the RF circuit 827). Moreover, the antenna unit 110 may be implementedby the antenna 810. In addition, the network communication unit 130 maybe implemented by the controller 821 and/or the network interface 823.Further, the storage unit 140 may be implemented by the memory 822.

Second Application Example

FIG. 15 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station apparatus 850, and an RRH 860. Each of the antennas 840and the RRH 860 may be connected to each other via an RF cable. Further,the base station apparatus 850 and the RRH 860 may be connected to eachother by a high speed line such as optical fiber cables.

Each of the antennas 840 includes a single or a plurality of antennaelements (e.g., antenna elements constituting a MIMO antenna), and isused for the RRH 860 to transmit and receive a wireless signal. The eNB830 may include a plurality of the antennas 840 as illustrated in FIG.15, and the plurality of antennas 840 may, for example, correspond to aplurality of frequency bands used by the eNB 830. Note that FIG. 15illustrates an example in which the eNB 830 includes the plurality ofantennas 840, but the eNB 830 may include the single antenna 840.

The base station apparatus 850 includes a controller 851, a memory 852,a network interface 853, a wireless communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are similar to the controller 821, the memory 822,and the network interface 823 described with reference to FIG. 14.

The wireless communication interface 855 supports a cellularcommunication system such as LTE and LTE-Advanced, and provides wirelessconnection to a terminal located in a sector corresponding to the RRH860 via the RRH 860 and the antenna 840. The wireless communicationinterface 855 may typically include a BB processor 856 or the like. TheBB processor 856 is similar to the BB processor 826 described withreference to FIG. 14 except that the BB processor 856 is connected to anRF circuit 864 of the RRH 860 via the connection interface 857. Thewireless communication interface 855 may include a plurality of the BBprocessors 856, as illustrated in FIG. 15, and the plurality of BBprocessors 856 may, for example, correspond to a plurality of frequencybands used by the eNB 830. Note that FIG. 15 illustrates an example inwhich the wireless communication interface 855 includes the plurality ofBB processors 856, but the wireless communication interface 855 mayinclude the single BB processor 856.

The connection interface 857 is an interface for connecting the basestation apparatus 850 (wireless communication interface 855) to the RRH860. The connection interface 857 may be a communication module forcommunication on the high speed line which connects the base stationapparatus 850 (wireless communication interface 855) to the RRH 860.

Further, the RRH 860 includes a connection interface 861 and a wirelesscommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(wireless communication interface 863) to the base station apparatus850. The connection interface 861 may be a communication module forcommunication on the high speed line.

The wireless communication interface 863 transmits and receives awireless signal via the antenna 840. The wireless communicationinterface 863 may typically include the RF circuit 864 or the like. TheRF circuit 864 may include a mixer, a filter, an amplifier and the like,and transmits and receives a wireless signal via the antenna 840. Thewireless communication interface 863 may include a plurality of the RFcircuits 864 as illustrated in FIG. 15, and the plurality of RF circuits864 may, for example, correspond to a plurality of antenna elements.Note that FIG. 15 illustrates an example in which the wirelesscommunication interface 863 includes the plurality of RF circuits 864,but the wireless communication interface 863 may include the single RFcircuit 864.

In the eNB 830 illustrated in FIG. 15, one or more structural elementsincluded in the small cell base station 10 (the transmission processingunit 151 and/or the reporting unit 153) described with reference to FIG.6 may be implemented by the wireless communication interface 855 and/orthe wireless communication interface 863. Alternatively, at least someof these structural elements may be implemented by the controller 851.As an example, a module which includes a part (for example, the BBprocessor 856) or all of the wireless communication interface 855 and/orthe controller 851 may be mounted in the eNB 830, and the one or morestructural elements may be implemented by the module. In this case, themodule may store a program for causing the processor to function as theone or more structural elements (i.e., a program for causing theprocessor to execute operations of the one or more structural elements)and may execute the program. As another example, the program for causingthe processor to function as the one or more structural elements may beinstalled in the eNB 830, and the wireless communication interface 855(for example, the BB processor 856) and/or the controller 851 mayexecute the program. As described above, the eNB 830, the base stationapparatus 850, or the module may be provided as an apparatus whichincludes the one or more structural elements, and the program forcausing the processor to function as the one or more structural elementsmay be provided. In addition, a readable recording medium in which theprogram is recorded may be provided.

In addition, in the eNB 830 illustrated in FIG. 15, for example, thewireless communication unit 120 described with reference to FIG. 6 maybe implemented by the wireless communication interface 863 (for example,the RF circuit 864). Moreover, the antenna unit 110 may be implementedby the antenna 840. In addition, the network communication unit 130 maybe implemented by the controller 851 and/or the network interface 853.Further, the storage unit 140 may be implemented by the memory 852.

4.2. Application Examples for Terminal Apparatus First ApplicationExample

FIG. 16 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which the technology according tothe present disclosure may be applied. The smartphone 900 includes aprocessor 901, a memory 902, a storage 903, an external connectioninterface 904, a camera 906, a sensor 907, a microphone 908, an inputdevice 909, a display device 910, a speaker 911, a wirelesscommunication interface 912, one or more antenna switches 915, one ormore antennas 916, a bus 917, a battery 918, and an auxiliary controller919.

The processor 901 may be, for example, a CPU or a system on chip (SoC),and controls the functions of an application layer and other layers ofthe smartphone 900. The memory 902 includes a RAM and a ROM, and storesa program executed by the processor 901 and data. The storage 903 mayinclude a storage medium such as semiconductor memories and hard disks.The external connection interface 904 is an interface for connecting thesmartphone 900 to an externally attached device such as memory cards anduniversal serial bus (USB) devices.

The camera 906 includes, for example, an image sensor such as chargecoupled devices (CCDs) and complementary metal oxide semiconductor(CMOS), and generates a captured image. The sensor 907 may include asensor group including, for example, a positioning sensor, a gyrosensor, a geomagnetic sensor, an acceleration sensor and the like. Themicrophone 908 converts a sound that is input into the smartphone 900 toan audio signal. The input device 909 includes, for example, a touchsensor which detects that a screen of the display device 910 is touched,a key pad, a keyboard, a button, a switch or the like, and accepts anoperation or an information input from a user. The display device 910includes a screen such as liquid crystal displays (LCDs) and organiclight emitting diode (OLED) displays, and displays an output image ofthe smartphone 900. The speaker 911 converts the audio signal that isoutput from the smartphone 900 to a sound.

The wireless communication interface 912 supports a cellularcommunication system such as LTE or LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 912 may typicallyinclude the BB processor 913, the RF circuit 914, and the like. The BBprocessor 913 may, for example, perform encoding/decoding,modulation/demodulation, multiplexing/demultiplexing, and the like, andperforms a variety of types of signal processing for wirelesscommunication. On the other hand, the RF circuit 914 may include amixer, a filter, an amplifier, and the like, and transmits and receivesa wireless signal via the antenna 916. The wireless communicationinterface 912 may be a one-chip module in which the BB processor 913 andthe RF circuit 914 are integrated. The wireless communication interface912 may include a plurality of BB processors 913 and a plurality of RFcircuits 914 as illustrated in FIG. 16. Note that FIG. 16 illustrates anexample in which the wireless communication interface 912 includes aplurality of BB processors 913 and a plurality of RF circuits 914, butthe wireless communication interface 912 may include a single BBprocessor 913 or a single RF circuit 914.

Further, the wireless communication interface 912 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelesslocal area network (LAN) system in addition to the cellularcommunication system, and in this case, the wireless communicationinterface 912 may include the BB processor 913 and the RF circuit 914for each wireless communication system.

Each antenna switch 915 switches a connection destination of the antenna916 among a plurality of circuits (for example, circuits for differentwireless communication systems) included in the wireless communicationinterface 912.

Each of the antennas 916 includes one or more antenna elements (forexample, a plurality of antenna elements constituting a MIMO antenna)and is used for transmission and reception of the wireless signal by thewireless communication interface 912. The smartphone 900 may include aplurality of antennas 916 as illustrated in FIG. 16. Note that FIG. 16illustrates an example in which the smartphone 900 includes a pluralityof antennas 916, but the smartphone 900 may include a single antenna916.

Further, the smartphone 900 may include the antenna 916 for eachwireless communication system. In this case, the antenna switch 915 maybe omitted from a configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the external connection interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the wireless communication interface 912, and the auxiliarycontroller 919 to each other. The battery 918 supplies electric power toeach block of the smartphone 900 illustrated in FIG. 16 via a feederline that is partially illustrated in the figure as a dashed line. Theauxiliary controller 919, for example, operates a minimally necessaryfunction of the smartphone 900 in a sleep mode.

In the smartphone 900 illustrated in FIG. 16, one or more structuralelements included in the terminal apparatus 20 (the measurementprocessing unit 241 and/or the requesting unit 243) described withreference to FIG. 7 may be implemented by the wireless communicationinterface 912. Alternatively, at least some of these structural elementsmay be implemented by the processor 901 or the auxiliary controller 919.As an example, a module which includes a part (for example, the BBprocessor 913) or all of the wireless communication interface 912, theprocessor 901, and/or the auxiliary controller 919 may be mounted in thesmartphone 900, and the one or more structural elements may beimplemented by the module. In this case, the module may store a programfor causing the processor to function as the one or more structuralelements (i.e., a program for causing the processor to executeoperations of the one or more structural elements) and may execute theprogram. As another example, the program for causing the processor tofunction as the one or more structural elements may be installed in thesmartphone 900, and the wireless communication interface 912 (forexample, the BB processor 913), the processor 901, and/or the auxiliarycontroller 919 may execute the program. As described above, thesmartphone 900 or the module may be provided as an apparatus whichincludes the one or more structural elements, and the program forcausing the processor to function as the one or more structural elementsmay be provided. In addition, a readable recording medium in which theprogram is recorded may be provided.

In addition, in the smartphone 900 illustrated in FIG. 16, for example,the wireless communication unit 220 described with reference to FIG. 7may be implemented by the wireless communication interface 912 (forexample, the RF circuit 914). Moreover, the antenna unit 210 may beimplemented by the antenna 916. Further, the storage unit 230 may beimplemented by the memory 902.

Second Application Example

FIG. 17 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus 920 to which the technologyaccording to the present disclosure may be applied. The car navigationapparatus 920 includes a processor 921, a memory 922, a globalpositioning system (GPS) module 924, a sensor 925, a data interface 926,a content player 927, a storage medium interface 928, an input device929, a display device 930, a speaker 931, a wireless communicationinterface 933, one or more antenna switches 936, one or more antennas937, and a battery 938.

The processor 921 may be, for example, a CPU or an SoC, and controls thenavigation function and the other functions of the car navigationapparatus 920. The memory 922 includes a RAM and a ROM, and stores aprogram executed by the processor 921 and data.

The GPS module 924 uses a GPS signal received from a GPS satellite tomeasure the position (e.g., latitude, longitude, and altitude) of thecar navigation apparatus 920. The sensor 925 may include a sensor groupincluding, for example, a gyro sensor, a geomagnetic sensor, abarometric sensor and the like. The data interface 926 is, for example,connected to an in-vehicle network 941 via a terminal that is notillustrated, and acquires data such as vehicle speed data generated onthe vehicle side.

The content player 927 reproduces content stored in a storage medium(e.g., CD or DVD) inserted into the storage medium interface 928. Theinput device 929 includes, for example, a touch sensor which detectsthat a screen of the display device 930 is touched, a button, a switchor the like, and accepts operation or information input from a user. Thedisplay device 930 includes a screen such as LCDs and OLED displays, anddisplays an image of the navigation function or the reproduced content.The speaker 931 outputs a sound of the navigation function or thereproduced content.

The wireless communication interface 933 supports a cellularcommunication system such as LTE or LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 933 may typicallyinclude the BB processor 934, the RF circuit 935, and the like. The BBprocessor 934 may, for example, perform encoding/decoding,modulation/demodulation, multiplexing/demultiplexing, and the like, andperforms a variety of types of signal processing for wirelesscommunication. On the other hand, the RF circuit 935 may include amixer, a filter, an amplifier, and the like, and transmits and receivesa wireless signal via the antenna 937. The wireless communicationinterface 933 may be a one-chip module in which the BB processor 934 andthe RF circuit 935 are integrated. The wireless communication interface933 may include a plurality of BB processors 934 and a plurality of RFcircuits 935 as illustrated in FIG. 17. Note that FIG. 17 illustrates anexample in which the wireless communication interface 933 includes aplurality of BB processors 934 and a plurality of RF circuits 935, butthe wireless communication interface 933 may include a single BBprocessor 934 or a single RF circuit 935.

Further, the wireless communication interface 933 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelessLAN system in addition to the cellular communication system, and in thiscase, the wireless communication interface 933 may include the BBprocessor 934 and the RF circuit 935 for each wireless communicationsystem.

Each antenna switch 936 switches a connection destination of the antenna937 among a plurality of circuits (for example, circuits for differentwireless communication systems) included in the wireless communicationinterface 933.

Each of the antennas 937 includes one or more antenna elements (forexample, a plurality of antenna elements constituting a MIMO antenna)and is used for transmission and reception of the wireless signal by thewireless communication interface 933. The car navigation apparatus 920may include a plurality of antennas 937 as illustrated in FIG. 17. Notethat FIG. 17 illustrates an example in which the car navigationapparatus 920 includes a plurality of antennas 937, but the carnavigation apparatus 920 may include a single antenna 937.

Further, the car navigation apparatus 920 may include the antenna 937for each wireless communication system. In this case, the antenna switch936 may be omitted from a configuration of the car navigation apparatus920.

The battery 938 supplies electric power to each block of the carnavigation apparatus 920 illustrated in FIG. 17 via a feeder line thatis partially illustrated in the figure as a dashed line. Further, thebattery 938 accumulates the electric power supplied from the vehicle.

In the car navigation apparatus 920 illustrated in FIG. 17, one or morestructural elements included in the terminal apparatus 20 (themeasurement processing unit 241 and/or the requesting unit 243)described with reference to FIG. 7 may be implemented by the wirelesscommunication interface 933. Alternatively, at least some of thesestructural elements may be implemented by the processor 921. As anexample, a module which includes a part (for example, the BB processor934) or all of the wireless communication interface 933 and/or theprocessor 921 may be mounted in the car navigation apparatus 920, andthe one or more structural elements may be implemented by the module. Inthis case, the module may store a program for causing the processor tofunction as the one or more structural elements (i.e., a program forcausing the processor to execute operations of the one or morestructural elements) and may execute the program. As another example,the program for causing the processor to function as the one or morestructural elements may be installed in the car navigation apparatus920, and the wireless communication interface 933 (for example, the BBprocessor 934) and/or the processor 921 may execute the program. Asdescribed above, the car navigation apparatus 920 or the module may beprovided as an apparatus which includes the one or more structuralelements, and the program for causing the processor to function as theone or more structural elements may be provided. In addition, a readablerecording medium in which the program is recorded may be provided.

In addition, in the car navigation apparatus 920 illustrated in FIG. 17,for example, the wireless communication unit 220 described withreference to FIG. 7 may be implemented by the wireless communicationinterface 933 (for example, the RF circuit 935). Moreover, the antennaunit 210 may be implemented by the antenna 937. Further, the storageunit 230 may be implemented by the memory 922.

The technology of the present disclosure may also be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of thecar navigation apparatus 920, the in-vehicle network 941, and a vehiclemodule 942. In other words, the in-vehicle system (or a vehicle) 940 maybe provided as an apparatus which includes the measurement processingunit 241 and the requesting unit 243. The vehicle module 942 generatesvehicle data such as vehicle speed, engine speed, and troubleinformation, and outputs the generated data to the in-vehicle network941.

6. Conclusion

An embodiment of the present disclosure has been described in detailwith reference to FIGS. 1 to 17. As described above, the small cell basestation 10 according to the present embodiment selects, from among oneor more unit frequency bands in an off state in a plurality of unitfrequency bands that may be brought into an on state for uplinkcommunication or downlink communication in a small cell, the unitfrequency band in an off state to be used for transmission of adiscovery signal to enable measurement in the unit frequency band in anoff state. Thus, the small cell base station 10 can transmit thediscovery signal selectively in a partial band of the broad milli-wavezone, which enables a reduction in power consumption and also areduction in inter-cell interference. This enables the system 1 toeffectively use a unit frequency band using the milli-wave zone, and canimprove traffic accommodation efficiency of the terminal apparatus 20 ina cellular network.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

Note that it is not necessary for the processing described in thisspecification with reference to the flowchart and the sequence diagramto be executed in the order shown in the flowchart and the sequencediagram. Some processing steps may be performed in parallel. Further,some of additional steps can be adopted, or some processing steps can beomitted.

Further, the effects described in this specification are merelyillustrative or exemplified effects, and are not limitative. That is,with or in the place of the above effects, the technology according tothe present disclosure may achieve other effects that are clear to thoseskilled in the art from the description of this specification.

Additionally, the present technology may also be configured as below.

(1)

An apparatus that operates a small cell, the apparatus including:

a processing unit configured to select, from among one or more unitfrequency bands in an off state in a plurality of unit frequency bandsthat may be brought into an on state for uplink communication ordownlink communication in the small cell, the unit frequency band in anoff state to be used for transmission of a discovery signal to enablemeasurement in the unit frequency band in an off state.

(2)

The apparatus according to (1), in which the processing unit reportsinformation indicating the unit frequency band to be used fortransmission of the discovery signal to a terminal that connects to thesmall cell.

(3)

The apparatus according to (2), in which the processing unit reports theinformation indicating the unit frequency band to be used fortransmission of the discovery signal to the terminal that connects tothe small cell, in a case where there is a change in the unit frequencyband to be used for transmission of the discovery signal.

(4)

The apparatus according to any one of (1) to (3), in which theprocessing unit reports information indicating the unit frequency bandcapable of being brought into an on state to a terminal that connects tothe small cell.

(5) The apparatus according to (4), in which the unit frequency bandcapable of being brought into an on state is associated with the unitfrequency band used for transmission of the discovery signal.(6)

The apparatus according to (5), in which the unit frequency band capableof being brought into an on state includes a band different from theassociated unit frequency band used for transmission of the discoverysignal.

(7)

The apparatus according to any one of (2) to (6), in which a physicaldownlink control channel (PDCCH) or system information is used for thereporting.

(8)

The apparatus according to any one of (2) to (7), in which theprocessing unit performs the reporting periodically.

(9)

The apparatus according to any one of (1) to (8), in which theprocessing unit increases or reduces the unit frequency band to be usedfor transmission of the discovery signal in a stepwise manner.

(10)

The apparatus according to any one of (1) to (9), in which theprocessing unit selects the unit frequency band to be used fortransmission of the discovery signal or selects the unit frequency bandto be brought into an on state or brought into an off state, on a basisof a measurement result of the discovery signal in a terminal thatconnects to the small cell.

(11)

The apparatus according to any one of (1) to (10), in which theprocessing unit selects the unit frequency band to be used fortransmission of the discovery signal or selects the unit frequency bandto be brought into an on state or brought into an off state, on a basisof a request from a terminal that connects to the small cell.

(12)

The apparatus according to any one of (1) to (11), in which theprocessing unit makes a transmission cycle of the discovery signaldiffer for each unit frequency band.

(13)

The apparatus according to (12), in which the processing unit makes thetransmission cycle of the discovery signal shorter for the unitfrequency band with a smaller bandwidth.

(14)

The apparatus according to any one of (1) to (13), in which the unitfrequency band is a component carrier in a frequency band of 6 GHz ormore.

(15)

An apparatus that connects to a small cell, the apparatus including:

a processing unit configured to perform measurement regarding adiscovery signal that has been transmitted using a unit frequency bandselected from one or more unit frequency bands in an off state in aplurality of unit frequency bands that may be brought into an on statefor uplink communication or downlink communication in the small cell.

(16)

The apparatus according to (15), in which the processing unit reportsinformation indicating the unit frequency band in an off state to berequested to be used for transmission of the discovery signal, to a basestation.

(17) The apparatus according to (15) or (16), in which the processingunit reports information indicating the unit frequency band to berequested to be brought into an on state, to a base station.(18)

The apparatus according to (16) or (17), in which the processing unitreports information indicating the unit frequency band related to therequest, together with a measurement report, to the base station.

(19)

A method including:

selecting, by a processor, from among one or more unit frequency bandsin an off state in a plurality of unit frequency bands that may bebrought into an on state for uplink communication or downlinkcommunication in a small cell, the unit frequency band in an off stateto be used for transmission of a discovery signal to enable measurementin the unit frequency band in an off state.

(20)

A method including:

performing, by a processor, measurement regarding a discovery signalthat has been transmitted using a unit frequency band selected from oneor more unit frequency bands in an off state in a plurality of unitfrequency bands that may be brought into an on state for uplinkcommunication or downlink communication in a small cell.

REFERENCE SIGNS LIST

-   1 system-   10 small cell base station-   11 small cell-   15 core network-   16 packet data network-   20 terminal apparatus-   30 macro cell base station-   31 macro cell-   110 antenna unit-   120 wireless communication unit-   130 network communication unit-   140 storage unit-   150 processing unit-   151 transmission processing unit-   153 reporting unit-   210 antenna unit-   220 wireless communication unit-   230 storage unit-   240 processing unit-   241 measurement processing unit-   243 requesting unit

1. An apparatus that operates a small cell, the apparatus comprising:processing circuitry configured to: select at least one of a pluralityof unit frequency bands that is in the off state to be indicated asbeing available for measurement, and indicate remaining of the pluralityof unit frequency bands that is in the off state as not being availablefor measurement; and transmit a measurement signal information report,the report including the indication of which of the plurality of unitfrequency bands that is in the off state is indicated as being availablefor measurement, and wherein the plurality of unit frequency bandsbelong to a milli-wave zone.
 2. The apparatus according to claim 1,wherein the processing circuitry reports information indicating the unitfrequency band to be used for transmission of the measurement signal toa terminal that connects to the small cell.
 3. The apparatus accordingto claim 2, wherein the processing circuitry reports the informationindicating the unit frequency band to be used for transmission of thediscovery measurement signal to the terminal that connects to the smallcell, in a case where there is a change in the unit frequency band to beused for transmission of the measurement signal.
 4. The apparatusaccording to claim 1, wherein the processing circuitry reportsinformation indicating the unit frequency band capable of being broughtinto an on state to a terminal that connects to the small cell.
 5. Theapparatus according to claim 4, wherein the unit frequency band capableof being brought into an on state is associated with the unit frequencyband used for transmission of the measurement signal.
 6. The apparatusaccording to claim 5, wherein the unit frequency band capable of beingbrought into an on state includes a band different from the associatedunit frequency band used for transmission of the measurement signal. 7.The apparatus according to claim 2, wherein a physical downlink controlchannel (PDCCH) or system information is used for the reporting.
 8. Theapparatus according to claim 2, wherein the processing circuitryperforms the reporting periodically.
 9. The apparatus according to claim1, wherein the processing circuitry increases or reduces the unitfrequency band to be used for transmission of the measurement signal ina stepwise manner.
 10. The apparatus according to claim 1, wherein theprocessing circuitry selects the unit frequency band to be used fortransmission of the measurement signal or selects the unit frequencyband to be brought into an on state or brought into an off state, on abasis of a measurement result of the measurement signal in a terminalthat connects to the small cell.
 11. The apparatus according to claim 1,wherein the processing circuitry selects the unit frequency band to beused for transmission of the measurement signal or selects the unitfrequency band to be brought into an on state or brought into an offstate, on a basis of a request from a terminal that connects to thesmall cell.
 12. The apparatus according to claim 1, wherein theprocessing circuitry makes a transmission cycle of the measurementsignal differ for each unit frequency band.
 13. The apparatus accordingto claim 12, wherein the processing circuitry makes the transmissioncycle of the measurement signal shorter for the unit frequency band witha smaller bandwidth.
 14. The apparatus according to claim 1, wherein theunit frequency band is a component carrier in a frequency band of 6 GHzor more.
 15. An apparatus that connects to a small cell, the apparatuscomprising: a processing circuitry configured to: receive a measurementsignal information report providing information of a plurality of unitfrequency bands that are in an off state and may be later brought intoan on state for uplink communication or downlink communication in thesmall cell; wherein the measurement signal information report indicatesat least one of the plurality of unit frequency bands that is in the offstate as being available for measurement while in the off state, andremaining of the plurality of unit frequency bands that is in the offstate is indicated as not available for measurement while in the offstate; and perform measurement, based upon the received measurementsignal information report, of a measurement signal that has beenreceived and that corresponds to the at least one of the plurality ofunit frequency bands that is in the off state that was indicated asbeing available for measurement while in the off state.
 16. Theapparatus according to claim 15, wherein the processing circuitryreports information indicating the unit frequency band to be requestedto be used for transmission of the measurement signal, to a basestation.
 17. The apparatus according to claim 15, wherein the processingcircuitry reports information indicating the unit frequency band to berequested to be brought into an on state, to a base station.
 18. Theapparatus according to claim 16, wherein the processing circuitryreports information indicating the unit frequency band related to therequest, together with a measurement report, to the base station.
 19. Amethod comprising: storing measurement signal information for each of aplurality of unit frequency bands that are each in an off state, whereinthe off state may be later brought into an on state for uplinkcommunication or downlink communication in the small cell; selecting atleast one of the plurality of unit frequency bands that is in the offstate to be indicated as being available for measurement while in theoff state, and indicate remaining of the plurality of unit frequencybands that is in the off state as not being available for measurementwhile in the off state; and transmitting a measurement signalinformation report, the report including the indication of which of theplurality of unit frequency bands that is in the off state is indicatedas being available for measurement while in the off state, and which ofthe remaining of the plurality of unit frequency bands that is in theoff state are not available for measurement while in the off state. 20.A method comprising: receiving a measurement signal information reportproviding information of a plurality of unit frequency bands that are inan off state and may be later brought into an on state for uplinkcommunication or downlink communication in the small cell; wherein themeasurement signal information report indicates at least one of theplurality of unit frequency bands that is in the off state as beingavailable for measurement while in the off state, and remaining of theplurality of unit frequency bands that is in the off state is indicatedas not available for measurement while in the off state; and performingmeasurement, based upon the received measurement signal informationreport, of a measurement signal that has been received and thatcorresponds to the at least one of the plurality of unit frequency bandsthat is in the off state that was indicated as being available formeasurement while in the off state.
 21. A non-transitory computerreadable storage device having computer readable instructions that whenexecuted by processing circuitry cause the processing circuitry toperform a method comprising: storing measurement signal information foreach of a plurality of unit frequency bands that are each in an offstate, wherein the off state may be later brought into an on state foruplink communication or downlink communication in the small cell;selecting at least one of the plurality of unit frequency bands that isin the off state to be indicated as being available for measurementwhile in the off state, and indicate remaining of the plurality of unitfrequency bands that is in the off state as not being available formeasurement while in the off state; and transmitting a measurementsignal information report, the report including the indication of whichof the plurality of unit frequency bands that is in the off state isindicated as being available for measurement while in the off state, andwhich of the remaining of the plurality of unit frequency bands that isin the off state are not available for measurement while in the offstate.
 22. A non-transitory computer readable storage device havingcomputer readable instructions that when executed by processingcircuitry cause the processing circuitry to perform a method comprising:receiving a measurement signal information report providing informationof a plurality of unit frequency bands that are in an off state and maybe later brought into an on state for uplink communication or downlinkcommunication in the small cell; wherein the measurement signalinformation report indicates at least one of the plurality of unitfrequency bands that is in the off state as being available formeasurement while in the off state, and remaining of the plurality ofunit frequency bands that is in the off state is indicated as notavailable for measurement while in the off state; and performingmeasurement, based upon the received measurement signal informationreport, of a measurement signal that has been received and thatcorresponds to the at least one of the plurality of unit frequency bandsthat is in the off state that was indicated as being available formeasurement while in the off state.